of akron



' Io nnwm Original Reiseued July 1 9, 1927.

, UNITED STATES PATENT OFFICE.

mmom) um: weanling or AKRON, orno, ASSIGNOR TO THE MILLER RUBBER comm, or AKRON, 01110, A conronarron or onro.

METHOD OF VULCANIZING RUBBER.

-ized while the other is completely unvul canized. For economic reasons it is desirable that the two compounds be united be- .-fore being subjected to vulcanization and this insures a better bond between the two plies.

Where it is desired that a rubber compound shou'ld vulcanize it is usual to mix therewith sulphur or some sulphur containing ingredient. Sulphur and rubber alone would require an extremely long time to vulcanize and, as sulphur is of migratory properties, during such slow vulcanization sul-- phur would migrate throughout not only the' stock in which it has been originally placed, 'but throughout the stock adjacent thereto in which sulphur had purposely been omitted. It is, therefore, evident that at least. partial vulcanization of the entire mass would 00- our and would defeat the attempt to secure a l-article, part of which was unvulcanized. In the past in order to prevent such a result, it has been found necessary to heavily com- {pound the stock which was to bevulcanized, and subjecting the articles to a high vulcanization temperature in attempts to substantially vulcanize the one stock before the other stock could attainappreciable vulcaniza'tion. Such attempts were not commercially reliable and the heavy compounding" usually resulted in an inferior article.

The above process was improved upon by Morton and Harrison (U. S. Patent No.

1,478,576) who found that by the use of non-migratory accelerators the temperature No. 1,540,580, dated June 2, 1 925,-Ser1a1 No. 721,076, filed .iune 19, 1924. Appliedtion for reissue filed May 81, 1927. serial No. 195,576.

required for vulcanization could be lowered .to a point where vulcanization of compounds not containing such accelerators was impossible and that at such temperatures the sulphur would migrate to the accelerator-conby the use of accelerators not suited to the Harnson and Morton process, due to their,

migratory nature.

In the search for a method of .usin migratory accelerators in situations simi ar to that described above, I have discovered a new class of compounding ingredients which from their nature I'choose to call vulcanization retarding agents. These materials when added to compounds of rubber have a retarding action on vulcanization, and, therefore, produce an action opposite to that produced by accelerators. suflicient quantities they prevent vulcanization completely.

Although my invention is applicable to the manufacture of various rubber articles and I do not care to confine my invention to any one article, as a matter of example I When added in could say that inner tube patching material I may be produced having one ply .unvulcani'zed and the other ply completely vulcanized. In manufacturing such an article the parts or plies which it is desired to remain unvulcanized are compounded from rubber,

sulphur, and vulcanization retarding mate rial, Whereas those parts or plles which are taining stock, but in the presence of the re tarding agent no vulcanizatiomwill occur.

As a specific example of sdch stocks I prepare two batches according to the followlng formulae:

Batch 1 I calender to a thickness of 1/64", and Batch 2 to a thickness of 1/32".

The two plies are super-imposed and placed in a heated oven for 20 hours at 180 F., when it will be found that the ply made from Batch 1 will be unvulcanized, whereas the ply made from Batch 2 will be completely vulcanized. In theabove example the dimethyl ammonium dimethyl-dithiocarbamate is the accelerator and stannous chloride is the retarding agent. The whiting is not necessary to the results, but is used as a filling ingredient. .Of'course other filling or coloring ingredients may be used, as will be understood by those skilled in the art. Also other migratory accelerators may be used in place of the one stated.

I have found stannous chloride to be an excellent retarding agent, but other chemicals have been found to perform in thesame manner. I have secured similar results with oxalic acid, potassium tetra-oxalate, citric acid, salicylic acid, tartaric acid, boric acid and succinic acid.

It will be understood that the retarder used is of a non-migratory nature.

In its broad aspect, my invention involves the discovery that by the use of one .of a class of agents I have called vulcanization retarders, vulcanization can be prevented in a ortion of a sheet or article so compounded and treated according to known procedure for effecting vulcanization that portions contiguous the first named portion will be vulcanized.

Having thus described my invention, what I claim 1s:

;1. The hereindescribed method of producin an article of rubber having one art vucanized and another part unvulcanized, which consists in mixing two separate stocks,

one containing rubber, sulphur and a vulcanization retarder, and the other rubber but no sulphur, juxtaposing said stocks, and subjecting the same to vulcanizing temperature. I

2. The hereindescribed method of producing an article of rubber having one part vulcanized and another part unvulcanized, which consists in mixing two separate stocks, one containing rubber, sulphur and a vulcanization retarder, and the other rubber, an accelerator and a zinc salt but no sulphur juxtaposing said stocks, and subject: ing the same to vulcanizing temperature.

3. The hereindescribed method of producing an articleof rubber having ane part vulcanized and another part unvulcanized, which consists in mixing two separate stocks, one containing rubber, sulphur and a vulcanization retarder, and the other rubber, a migratory accelerator and a zinc salt, but no sulphur, juxtaposing said stocks, and

subjecting the same to vulcanizing temperature.

4. The hereindescribed method of producing a sheet of rubber comprising two layers one of which is vulcanized and the other unvulcanized, which consists in compounding two stocks, one containing rubber, sulphur and a vulcanization retarder, and the other rubber but no sulphur, forming said stocks into sheets, superimposing said sheetsyone on the other, and subjecting the same to a vulcanizing temperature.

- 5., The hereindescribed method of producing a sheet of rubber comprising two layers one of which is vulcanized and the other unvulcanized, which consists in compounding two stocks, one containing rubber, sulphur and a vulcanization retarder, and the other rubber, an accelerator and a zinc salt, but no sulphur, forming said stocks into sheets, superimposing said sheets one on the other, and subjecting the same to a vulcan- Y izing temperautre. v

6. The hereindescribed method of making an article having one part of vulcanized rubher and another part of unvulcanized rubber, which consists in mixing two separate stocks one containing rubber, sulphur and a vulcanization retarder, and the other rubber but no suluhur, juxtaposing said stocks in shape to form the desired article, and subjecting to curing temperature.

7. The hereindescribed method of making an article having one part of vulcanized rubber and another part of unvulcanized rubber, which consists in mixingtwo separate stocks one containing rubber, sulphur and a vulcanization retarder, and the other rubber, an accelerator and a zinc salt but no sulphur, juxtaposing said stocks in shape to form the desired article, and subjecting to curing temperature.

8. The hereindescribed method of treating rubber which consists in incor rating in a sulphur-containing portion t greof a vulcanization retarder and thensubjecting the article to'heat.

9. The method of treating rubber which consists in vulcanizing the rubber in the presence of stannous chloride acting as a retarder.

10: Masses and articles containing rubber, the vulcanization of which is retarded by the presence of stannous chloride.

11. As an article of manufacture, a rubber patch material consisting of a vulcanized ply and a superimposed unvulcanized ply,

, united to each other by vulcanizationthe vulcanization of the vulcanizedpart of the patch having been obtained by the use of sulphur as a vulcanizing agent, and the unvulcanized portion having been obtained by the use therein of a' vulcanization retarder.

12. A sheet or article formed from a rubber compound having one part-in a substantially diiierent condition as to state of vulcanization from another part, such different conditions being effected by the use of avulcanization retarder.

13. The method relating to the manufacture of multi-plypatching rubber which consists in introducing into one of the plies,

prior to subjecting said rubber .to a vulcanization temperature, a substance which acts to retard vulcamzation.

14. Masses and articles formed from a rub 'ber compound having'the vulcanization of portions thereof retarded by the presence ofv a vulcanization retarding agent, substantially as described. 15. An article formed by subjecting a rubber compound to vulcanization, said. article 7 having a part unvulcanized due to the presence of-a vulcanization retarder, substantially as described.

16. The method of producing by vulcani-' zation an article from a mass including rubber and compounding ingredients and in which sulphur is employed as a vulcanizing agent, involving the step of introducing into a part of the mass an ingredient having the property of retarding vulcanization.

17., The method of producing a sheet or article formed from a rubber mass for obtaining difi'erent conditions as to state of vulcanization in different parts thereof, in-

volving the treatment of one part of the mass by a normally migratory agent having the property of effecting vulcanization,

and the step of introducinginto another,

part of the mass an agent having the property of retarding vulcanization.

'18. A method relating to the manufacture of rubber articles having a part vulcanized and apart unvulcanized, which consists in introducing into the compound not later than the subjection of the article to a vulcanizing temperature, an agent for causing vulcanization and an agent having the property of accelerating vulcanization, and. also introducing into the portion of the an ingredient having-the property of retarding vulcanization. i

19. In the manufacture of an article having a part vulcanized and a part unvulcanized, a stock comprising rubber and compounding ingredients including sulphur and an agent having theproperty of retarding vulcanization localized in the stock.

20. The method of retarding vulcanization at a localized part of a normally: vulcanizable stock consisting. in introducing into said part an agent having the property'of retarding vulcanization.

In testimony whereof I aifix my signature.

RAYMOND MARK WARNER.

[compound which is to remain unvulcanized 

